Answer:
Time = 1.36s
Explanation:
coefficient of kinetic friction = μk
μk = F/N = F / mg
where m = mass of the body
g = acceleration due to gravity.
Doubling the force on the box we have,
μk = 2ma/mg
hence μk = 0.15/2 = 0.075
To determine the time it takes to reach a velocity of 2m/s from 1m/s .
From Newton law of motion,
v = u + a*t
for a deceleration of a = μk x g
2m/s = 1m/s + 0.075 x 9.8m/s² x t
t = (2m/s - 1m/s)/0.735m/s²
t = 1.36 seconds..
it will take the 1.36s for the crate to double to 2.0m/s
Answer:
(a) The self inductance, L = 21.95 mH
(b) The energy stored, E = 4.84 J
(c) the time, t = 0.154 s
Explanation:
(a) Self inductance is calculated as;
where;
N is the number of turns = 1000 loops
μ is the permeability of free space = 4π x 10⁻⁷ H/m
l is the length of the inductor, = 45 cm = 0.45 m
A is the area of the inductor (given diameter = 10 cm = 0.1 m)
(b) The energy stored in the inductor when 21 A current ;
(c) time it can be turned off if the induced emf cannot exceed 3.0 V;
Answer:
Boiling water - The heat passes from the burner into the pot, heating the water at the bottom. Then, this hot water rises and cooler water moves down to replace it, causing a circular motion.
Radiator - Puts warm air out at the top and draws in cooler air at the bottom.
Steaming cup of hot tea - The steam is showing heat being transfered into the air.
Ice melting - Heat moves to the ice from the air. This causes the melting from a solid to liquid.
Hot air balloon - A heater inside the balloon heats the air and so the air moves upward. This causes the balloon to rise because the hot air gets trapped inside. When the pilot want to descend, he releases some of the hot air and cool air takes it place, causing the balloon to lower.
Frozen material thawing - Frozen food thaws more quickly under cold running water that if it is placed in water. The action of the running water transfers heat into the food faster.
The answer is false. many famouse scientist used the very scientific theory that we use today